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Thread: VOD stream validation problem for iOS devices

  1. #1
    Join Date
    Jan 2012
    Posts
    2

    Default VOD stream validation problem for iOS devices

    I am trying using Wowza to stream adaptive bitrate video to iPhones, and although it does work, I get some really ugly errors from the stream validator that apple provides.


    --------------------------------------------------------------------------------
    /test/_definst_/mp4:test1-400x224-200.mov/playlist.m3u8?wowzasessionid=1835117553
    --------------------------------------------------------------------------------

    Playlist Validation:

    OK

    Segments:

    media_1.ts?wowzasessionid=1835117553:

    WARNING: Unable to read video timestamps in track 0; this may be due to not having a key frame in this segment.
    WARNING: Unable to read decode timestamps in track 0; this may be due to not having a key frame in this segment.
    WARNING: Unable to read video timestamps in track 1; this may be due to not having a key frame in this segment.
    WARNING: Unable to read decode timestamps in track 1; this may be due to not having a key frame in this segment.

    media_7.ts?wowzasessionid=1835117553:

    WARNING: Media segment exceeds target duration of 1.00 seconds by 95442.72 seconds (segment duration is 95443.72 seconds)

    Average segment duration: 13643.35 seconds
    Average segment bitrate: 220035.00 bps
    Average segment structural overhead: 25355.11 bps (11.52 %)


    The segment length bit really worries me, since I am using the default 10sec chunk length in Wowza, and have verified the chunks are actually that long by downloading them from Wowza. Is Wowza not adding certain flags or metadata to the chunks that apple may be requiring?

    The keyframe bit is also worrisome since my files are encoded with keyframes placed exactly every two seconds, so there should be at least a few in each 10sec chunk. Apple's stream validator clearly isn't seeing them, so there's some sort of compatibility issue here it seems.

    Any thoughts or suggestions would be greatly appreciated.

  2. #2
    Join Date
    Sep 2011
    Posts
    1,708

    Default

    Hi
    I don't think it's the keyframes, if the timestamps are in a format that the validator can't read then this is the kind of message you would receive.

    Jason

  3. #3
    Join Date
    Jan 2012
    Posts
    2

    Default

    I guess I'm not too familiar with where the timestamps live in the various types of files. Would you have any suggestion on what I might tweak or look at when encoding with ffmpeg/x264? Thanks!

  4. #4
    Join Date
    Dec 2007
    Posts
    28,412

    Default

    You probably do not have to worry about the WARNING lines.

    You can fine-tune results of this test by adjusting system-bitrate in each item of the smil. The actual bitrate must be with -+ 10% of target. The target is system-bitrate, which you can change.

    Richard

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